Synchronization under a commercial operating system

Mutual exclusion and general synchronization of concurrent processes (‘tasks’) are well-known principles for constructing reliable real-time systems. This paper shows how to implement these principles under a typical commercial operating system which provides incomplete synchronization operations. The problem of synchronizing erroneous tasks is discussed briefly.     

UTRA/FDD RF Transceiver Requirements

Unified RF requirements are derived for an UMTS Terrestrial RadioAccess/Frequency Division Duplex (UTRA/FDD) compliant mobile transceiver. Aset of transceiver requirements are proposed with consideration to systemissues including duplex aspects. From these design-compatible requirements areproposed for each functional block in the transceiver.     

Interquarter comparison of markers of subclinical mastitis: somatic cell count, electrical conductivity, N-acetyl-beta-glucosaminidase and antitrypsin.

We have evaluated the usefulness in mastitis diagnostics of new diagnostic measures using the continuous nature of the variation in quarter milk samples of four inflammatory markers: somatic cell count, N-acetyl-beta-glucosaminidase (EC 3.2.1.30), electrical conductivity and antitrypsin. A two-way analysis of variance was performed for each of the inflammatory markers on results from 273 cows sampled six times at 14 d intervals. Adjustment for the individual cow's mean removed approximately half the total variation for all four markers, indicating that comparisons in marker levels between quarters without taking the cows' overall level into account, as is done in diagnostic keys based on fixed threshold, is a rash procedure. After adjusting for the individual cow means, the total variation of the marker observations was partitioned in three sources of variation: between the four quarter levels, between different sampling days, and the experimental error, i.e. the variation within each quarter over the study period. As expected, the variation between quarters accounted for the largest percentage of the variation (44-65%). In contrast the variation between days was only 16-34% and of the same magnitude as the experimental error. These figures can profitably be taken into account when designing experiments in future mastitis research studies. They imply that mastitis diagnostics based on quarter milk samples collected over time will be influenced only slightly by random biological variation and that the same relative differences that exist in marker levels between the four quarters of a cow as a rule will be disclosed irrespective of sampling day. Thus, the udder health state is relatively stable when determined by these inflammatory markers. In addition to simple correlations between markers measured on the same day, correlations of the logarithm of the interquarter ratios and of the experimental errors were computed. Stronger associations between the markers emerged and these correlations reflect more precisely than simple correlations the real diagnostic relations of the markers.     

The specificity requirements of bacteriophage T4 lysozyme

The role of the sinoatrial ring bundle (SARB) in internodal conduction was examined by the microelectrode technique in excised rabbit hearts. The spread of the sinus impluse to the surrounding tissues was shown to proceed anteriorly toward the right branch of the crista terminalis significantly faster than toward the other direction. Thus the right SARB and the right branch of the crista terminalis close to the sinus node were the earliest areas excited by the sinus impulse in the areas surrounding the sinus node. It was further shown that the activation sequence does not initiate from the right SARB to the right branch of the crista terminalis via the junction of these two structures. Cutting the SARB did not produce any delay in conduction from the sinus node to the atrioventricular (AV) node. The conduction velocity measured at the endocardial surface by two microelectrodes has proved that conduction in the crista terminalis was significantly faster than in the SARB. The upstroke of the action potential from the crista terminalis was also steeper than that from the SARB. These results suggest that the SARB is not the main route for impulse propagation from the sinus node to the AV node; the fastest internodal conduction therefore takes place with wide wave fronts, along the crista terminalis.     

Determination of background serum density for lipoprotein ultracentrifugation

It is necessary to know the density of serum exclusive of its macromolecules (background density) prior to density adjustment with solid potassium bromide for ultra-centrifugal separation of lipoprotein fractions. To evaluate this, we compared the densities of the corresponding ultrafiltrates or dialysates of both human and equine sera produced by ultrafiltration and equilibrium dialysis method for macromolecule removal. Excellent correlation is found between background densities determined following ultrafiltration or equilibrium dialysis. These data validate the use of ultrafiltration as a simple, direct method for determination of background serum densities but reveal equilibrium dialysis to be more time consuming and less precise. Using ultrafiltration, we find the background density for equine serum to be 1.004 g/ml, and initial investigation suggests this value may be altered by freezing, prolonged refrigeration (3 months), or heating to inactivate lecithin: cholesterol acyltransferase.     

International studies of human factors in teleinformatics

This paper presents the history and context of the COST II bis work on human factors in teleinformatics. It describes the technical developments to be expected in networked systems which will change the capabilities that will be available to users and discusses the range of human-factors issues which will arise if users are to be able to master complex systems. The paper concludes by reporting the early debates of the working group and the classification of issues which identified the problems requiring human-factors attention     

Electromigration of hydrogen and deuterium in vanadium and niobium by a resistance method

The electric mobility of hydrogen and deuterium has been measured at 30°C in niobium (Cb) and vanadium by a resistance method. The electric mobility was found to be 5.7 × 10⁻⁴ cm²/V-s for hydrogen and 2.8 × 10⁻⁴ for deuterium in niobium. In vanadium the electric mobilities were 2.3 × 10⁻³ and 1.3 × 10⁻³ cm²/V-s for hydrogen and deuterium respectively. The effective charges calculated using reported diffusion coefficients are positive and are slightly greater for deuterium than for hydrogen in both vanadium and niobium. The resistivity increase due to the hydrogen isotopes in vanadium and niobium was also measured. Hydrogen was found to contribute 0.65 μ ohm-cm/at, pct and deuter-ium 0.58 μ ohm−cm/at, pct to the resistivity of niobium. In vanadium, the solute resistivi-ties were found to be 0.98 μ. ohm-cm/at, pct and 0.90 μ ohm−cm/at, pct for hydrogen and deuterium respectively. C. L. JENSEN, formerly a Graduate Student, Department of Materials Science and Engineering, Iowa State University